I bought a K'NEX roller coaster kit and helped him put it together. At first, he didn't grok the pseudo 3D instructions or the way the pieces fit together. However, after an hour or so, he was rotating our partially assembled segments in his head to compare them to the illustrations. But, this doesn't count as rigorous seat work. Oh well.
Our school actually does an excellent job of avoiding the binary incentives of No-Child-Left-Behind and attempts to provide somewhat individualized instruction to students. Ohio has yet to adopt a value-added measurement scheme, and I wonder how our district would fare, especially if achievement was normalized for socio-economic status (the average household income is over $100K, a high number for Ohio).
We hope that the Montessori school's motivated teachers can use their freedom from mandated curriculum requirements, standardized testing, etc. to facilitate our son's exploration of what interests him. I don't care if his education is seen as incomplete, unbalanced, or otherwise non-standard so long as he grows to become a curious, thoughtful, and creative person. When has someone with these qualities ever failed because he had some perceived weakness in his childhood education?